Farm Progress

As difficult as water cutbacks are, they pale in comparison to the biggest challenge California cotton has faced in its 100-year history — Fusarium Race 4.

Harry Cline 1

April 18, 2013

9 Min Read
<p> Aerial view of a field infected with Race 4.</p>

Despite strong world demand for Pima cotton and prices to reflect it, California cotton acreage will tumble once again, this time to below 300,000 acres this season.

Acala/upland acreage is projected to be down to just 90,000 acres, down 37 percent from last year, according to USDA-NASS. Pima, which represents almost 70 percent of the state’s cotton acreage, is projected to be 190,000 acres, down 16 percent from a year ago.

It is getting precariously close to the 300,000 to 350,000 acres experts say is needed to support a viable infrastructure of ginning, warehousing and trucking. However, cotton survived lower acreages in 2008 and 2009. If realized, the 280,000 acres projected for this season will be the third lowest acreage since 1935.

Price has everything to do with what farmers plant. However, cotton prices are not that bad, especially for Pima. Worldwide demand for U.S. Extra Long Staple cotton is strong. Jesse Curlee, president of Supima, said exports could reach 800,000 bales this year, which would make it the second largest export season in history. “The world economy is improving, and demand is going to be good in the future for Pima,” Curlee says. However, Curlee said at the California Cotton Growers Association annual meeting, 2013 acreage could be down 25 percent to 30 percent based on what he has been hearing from growers. “I hope it is not down as far as people are saying,” he lamented.


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Cotton is caught up in California’s water crisis. Water is impacting cotton acreage far more than price. State and federal water agencies have cut back water deliveries this year to the lowest level in four years. Competing with cotton for that water are increasingly more orchards and vineyards. What water growers receive from state and federal water agencies will go to trees and vines before it is used to produce cotton. Farmers fallow open ground and are forced to rely upon groundwater when surface deliveries are cut back. However, well water is often high in minerals which are not good for trees, particularly almonds. Therefore, scarce surface water goes to permanent crops.

Cotton also competes for water with higher value contract field crops, like processing tomatoes and vegetables.

Biggest challenge ever

As challenging as water may be, it pales in comparison to the biggest challenge California cotton has faced in its 100-year history, FOV (Fusarium) Race 4. It is a soil borne pathogen that can render fields unsuitable for cotton farming forever.

It is also a threat that has consequences far beyond California. The Golden State is a significant source for cotton planting seed across the Cotton Belt, due to ideal growing conditions. The California Crop Improvement Association is taking added measures to ensure that seed fields are not infected with Race 4.

Race 4 is not spread by nematodes like other Fusarium races. It is spread primarily in the movement of soil and infected plant debris. It can also be spread on infected planting seed as well as tailwater containing soil particles from infected fields.

California Cotton Growers and Ginners Associations President Earl William unequivocally calls Race 4 “the biggest threat to the California cotton industry.”

Already some growers have red-lined fields never to be planted to cotton again because of widespread Race 4, which only effects cotton.

The industry may be small in comparison to years past, but it is fighting back with all available resources to turn back the Race 4 threat with an aggressive research and informational program.

The ultimate solution is resistant varieties. Already, there are several Pimas highly resistant and some promising Acalas.

The second line of attack is to contain Race 4 when found and minimize its spread.

University of California Extension cotton specialist Bob Hutmacher said the spread of the pathogen is “slowing down,” partly because of reduced cotton acreage, but partly because of the better understanding by growers and Pest Control Advisers (PCAs) of the problem. California Cotton Growers Association has spearheaded an aggressive information campaign to spread the word of the threat and offer recommendations to hold it in check.


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A decade ago when the problem first surfaced, Race 4 was a pariah. Growers did not want others to know they had infected fields. Their fear was that it would reduce land values. It did in Australia where growers also have a Race 4 problem.

Hutmacher said California growers want to know if there is a problem and how to deal with it. Hutmacher said he made farm calls to 90 or 100 fields last year where growers wanted an assessment from him.

“Growers are pretty cognizant and concerned about the problem. They have a better understanding that is important to protect the industry, particularly to protect seed fields,” he said.

“We have the good misfortune you might say of having access to some really good Race 4 (infected) fields where we can evaluate varieties and conduct other research,” he said. The Cotton Alliance and the cotton growers association have stepped up with funding for a post doctoral student to work in the research program this summer. Cotton Incorporated also has contributed to the research effort. USDA-ARS continues to support research, as well.

Shafter setback

The battle looked like it suffered a major setback when USDA-ARS pulled out of the Cotton Research Station in Shafter a couple of years ago. There were two scientists there working almost exclusively on Race 4.

Fortunately, one of those two scientists continues to research germplasm for FOV resistant varieties.

USDA research geneticist Mauricio Ulloa was moved from Shafter to Lubbock, Texas, where his primary research responsibilities are developing drought and heat tolerant cotton germplasm.

“Fortunately,” said Hutmacher, “USDA-ARS administrators recognized the importance of Mauricio’s work from Shafter to allow him to continue his Race 4 work.”

“Mauricio’s background in molecular genetics, and the fact he has been working along with the rest of us for 10 years on the problem is a big plus.”

Ulloa’s goal is to provide Race 4 resistant germplasm to commercial plant breeders to develop new varieties.

Another key person in finding solutions to Race 4 is UC Davis plant pathologist Mike Davis. He was the first to identify it. He remains active in the team effort and has picked up some of the research the other Shafter scientist was doing. Rebecca Bennett has been working on seed treatments for Fusarium, but she is no longer researching that area in her new post in Arkansas.

What do growers do in the meantime until more resistant varieties are released?


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First is to identify it. If Race 4 is confirmed, growers should avoid moving soil and water from a contaminated field to a clean field. Hutmacher said it is a good idea to clearly mark contamination areas and change cultivation practices to avoid it.

Davis and Bennett have done enough research to verify that

Vapam spot treatments offer some benefits in knocking down inoculum populations. “It will not eradicate Race 4. Nothing will at this point,” he added.

“We continue to look at seed treatments, but so far they offer little value,” he said. There are biological materials that reportedly change soil conditions to suppress inoculum levels and Hutmacher will continue to look at those.

Agricultural pariah

Australians are looking at crop rotation with small grains and rice, but there has not been a lot of success, Hutmacher added. UC research has validated that inoculum levels can be reduced with rotation, but when susceptible varieties are planted back into a field with Race 4, the disease level will return quickly to damaging levels.

Fortunately, there are a few Race 4 resistant varieties available. Most are Pimas. Phytogen 800 and 802 RF and Deltapine 360 lead the pack. DP 385 RF and Phy 811 RF have looked promising in short-term trials.

Initially, Race 4 seemed to be confined to Pimas, but Upland/Acalas are also susceptible, and Hutmacher has greatly increased upland evaluations over the past three years. He identified several experimentals that showed high levels of resistance last season in his trials.

“Growers have some very good resistant Pima variety choices,   and seed companies seem to be pretty aggressive in their efforts as well,” Hutmacher said. Ulloa has released four highly resistant cultivars this year, all Pima with hopefully some uplands to follow.

Race 4 came in for considerable discussion at the Beltwide Cotton Conference this year. “It was mostly pathologists comparing notes on what they have found,” Hutmacher explained. With new molecular marker technology, scientists are able to better segregate Fusarium races. Fortunately, Race 4 has not been found outside of California, nor has an Australian strain of a similar race been identified in the U.S.

Nevertheless, other areas of the Belt have reason to be concerned about Race 4. Logic says the likelihood of spread is good.

“Based on what we’ve seen in California, Race 4 can spread in a relatively short time,” he said, adding that a non-Race 4 Fusarium spread quickly between the lettuce production areas of the San Joaquin Valley, the Salinas Valley and the southwest Arizona desert vegetable production areas despite the lettuce industry’s rigorous equipment cleaning protocol.

California agriculture is often the leader in new things. Unfortunately, it’s the guinea pig for a pariah no one wants. “We are certainly gaining a lot of experience in Race 4,” that may come in handy if it spreads.

The stepped up research effort, Hutmacher said, is another example of the cotton industry being pro-active. “It’s all about identifying issues and stepping up to the plate in providing funding to address the problem,” he said.

Another example of that is the cotton growers association’s leadership in developing an uncomplicated test to determine if Race 4 is in a field.

Paul Clark, business development manager for Agdia, told growers at the association’s annual meeting his company has developed a simple test growers and PCAs can use to identify Race 4.

Agdia, based in Indiana, was founded in 1981 and has developed 200 tests to detect various plant pathogens.

Normally, it takes from 7 days to 7 weeks to get results back from a lab. The Agdia test takes 30 to 40 minutes and can be performed on a pickup tailgate.

Agdia sells a kit that allows growers to test tissue samples for Race 4 in a five-step process.

“It is very specific to Race 4,” Clark said.

The testing equipment comes with 8 test kits. The initial cost is about $500, which includes the equipment to analyze a sample. Packets for taking eight individual samples cost about $240.

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